Large umbrellas are commonplace in a variety of settings to provide shade and otherwise protect individuals from the elements. These umbrellas usually are found in outdoor environments such as patios or outdoor restaurants, and often are used to shade individuals from exposure to direct sunlight. Such umbrellas are usually supported at one end of a central pole that extends downwardly to a stand or support resting on the ground and having sufficient mass or footing to maintain the umbrella upright. If the umbrella is used in connection with a table, the umbrella pole usually extends through a central hole in the table and engages an umbrella base located beneath the table so that the table and the base provide lateral support for the umbrella. To provide the most effective shade, umbrellas of this kind usually are selectably tiltable with respect to the umbrella pole so as to provide maximum shading area during times when the sun is not directly overhead, and the mass of a tilted umbrella is shifted from alignment with the central pole.
Although conventional center-pole umbrellas enjoy widespread use, such umbrellas have certain disadvantages. For example, center pole umbrellas generally are used only in combination with a table having a central opening designed to receive and support the umbrella pole. Without the central support provided by the table, the typical large umbrella becomes unstable and subject to tipping or overturning, particularly when the umbrella is tilted so that its center of mass becomes displaced from the center line of the umbrella pole. Because large umbrellas usually are relatively heavy, an overturned umbrella could injure anyone in its path of collapse. Moreover, umbrellas limited to use with a table or other central support are inconvenient where conventional table seating is not preferred. In any case, the conventional center pole umbrella is not convenient or appropriate for all applications.
Attempts have been made in the art to provide shade umbrellas supported at one side, thereby doing away with the central pole. Examples of such side-support umbrellas or sunshades are described in U.S. Pat. Nos. 3,383,814 and 4,586,525; and in PCT publication WO 82/03538. However, side mounting umbrellas as proposed in the prior art have not found widespread acceptance, perhaps because of the structural complexity or expense of such umbrellas. Furthermore, an umbrella effective for providing shade must be readily and conveniently tiltable from the conventional horizontal or upright position to various angles of tilt for providing effective shade throughout the day. The umbrella also must be easily erected at the start of the day and readily collapsed at day's end, preferably without requiring great physical strength by anyone manipulating the umbrella.